Valve spring



July 2l, 1931.

B. CATALINE ETAL VALVE SPRING Filed Ot. 19. 1927 Patented July 21, 1931UNITED stares vai"enr einer.I

BENTON GATALIN AND EUGENE C. RICHARD, O-F FLEET, IVICHIGAN, ASSl'GNORST0 GENERAL morons oon-nonfiction, DELAWARE OlV BETE-01T, MICHIGN, ACOPORATIGN GF VALVE srnrne Original application led December 10,V 1926,VSerial No. 153,822. vDivided and this application filed october 19,1927. serial no. 227,154.

This invention relates to motor Yvehicles and particularly tothe springsused in the operation of cam actuated valves of the internal combustionengines thereof.` l

rlhis application is a division of our prior application Ser. No.153,822, filed December l0, i926, and differs therefrom in that thelower coils of the spring of the present application have' 'aprogressively varying pitch in! stead of a constant one. p f

Owing to the high speed at Which modern internal combustion enginesmustoperate, it has been determined that the valve spring must build upa maximum spring pressure in 16 l/l80 of a Vsecond at 3600 R. P. M.motor speed, and this pressure must be immediate ly released and themechanism brought to. a stolp in an equal length of time.

e. s each spring has'anappreciable Weight 20 in each coil there is atendency for each coil,

due to its inertia, to. remain behind When the spring is releasedandthis tendency to lag will be increased as the Weight: andnumber ofcoils is increased. This condition con- `215 nection With the rapidreversal of action .of

the spring causes a series of vibrations Within the spring vvhichisknown as dancing` and this dancing produces4 objectionable noise,especially ywhen it synchronizes with so-me other sound or vibration ofthe motor, and alsoA causes a fluttering ofthe valve. This y dancing7 isinjurious tothe lifeV of the spring ways throughoutits range of Aactionthe full number of coils With their corresponding Weight to causedancingof the coils. lt has been found through a series of experimentswith springs of different sized Wire and number of coils that the Weightof the wire in the free coils directly affected the vdancing of thecoils. Bydecreasing the size ofthe Wire and number of active coils thedancing diminished and began to show only at certain intervals of speed.Therefore, it became the problem to produce aspring in which thedancing, if it occurred atall, Was outside the driving range of themotor.

Vle found that if We had a spring of several coils of'light Wire, whichwould close solid just before the maximumv opening of theV valve, andplaced it on a spring of one or two coils of heavy Wire, the dancing ofthe coils Was practically nil, `but the one or two coils Were taking allof the load and the variations in manufacture were such that the stressand load were built up to such an extent that the coils broke. discoverythat We'couldplace the coils that ivere to compress solid on the bottomand inake the free 'or upper coils. of a different pitch and thus. havea continuous spring as is shown inthe drawings.

In. the conventional type.A of valve spring, the frequency of naturalVvibration of the coils ofthe spring is quite deiinitcso periods ofvibration occur When the springs are operating in connection with thevalve mechanism of gasolineengines. The forni of the operating cam hasan influence upon the violence of these periods and with certainstructures critical points occur at quiteV frequentv intervalsv alongthe ,speed range. A remedy for this condition consists of Theseexperiments led `to our i placing closed coils at one end of the spring.Y

1When a spring of this type is observedin op-V eration by means of asuitable instrument, it is found that at the critical points Where thecoilsof the spring oscillate violently, the

closed coils open slightly which has the eficct of damping the vibrationof the spring. In order for the closed coils to operate, however, thespring vibration must be so violent as practically to lift the springclear of the valve spring retainer'.

It seems more desirable, therefore, to form the end coils in a helix ofdecreasing pitch as the end is approached. The end three coils, 'forexample, would decrease in pitch from a normal spacing between coilsdown to a point where the coils were touching at the very end. Then thespring is compressed by the valve spring retainer, some of the coils ofdecreased pitch will be closed, but the tension will be present in thewire so when any of the normal pressure is removed the closed coils willbreak contact for a certain distance, depending upon the extent of thedisturbance from normal operation.

lith this structure, therefore, when there is the slightest tendency todance or surge, the presence of dancing or surging will automaticallyvary the length of the spring so as to change its periodicity. Asidefrom this, the opening and closing of a portion of the coils, with oilpresent, will have a damping effect on the surge. It will not benecessary for the surge to become violent in order that the remedy maybecome eective.

In the drawings:

Figure 1 is a section through the valve operating means of an internalcombustion engine having a plurality of cylinders.

Figure 2 shows a free length of untensiened view of our spring.

Figure 3 shows the spring compressed as it appears in valve-closedposition, the arrow representing the load.

Figure 4 is a view similar to Figure 3 but with the valve in openposition.

In the drawings 1 designates an internal combustion engine of theconventional type, 2 one of the stems operated from the cam shaft (notshown), 3 a rocker for operating the valve stem 4, having the valve andoperating through the sleeve 6., This sleeve 6 has an integral collar 7seated on the engine block and confined between this collar and a secondcollar 8, secured to the upper end of the valve stem 4, is the spring 9,while a second spring 10, which forms the object of our invention, isconfined between the engine block and the collar 8, and surrounds thespring 9.

As will be seen from Figure 2, which shows the free length of thespring, the lower coils 11 are of a diierent pitch than the upper oractive coils 12. This pitch increases from the end of the spring at aupward toward the middle, the pitch of the successive coils beingslightly greater than the precedmg one.

As shown in Figure 2 the pitch at the two end coils is equal to thedistance a, while at the second and third coils the pitch is equal todistance b, which is somewhat greater than the distance a. The distancesindicated at c, al and e are each progressively greater giving aprogressively increased variation or difference in the pitch of thecoils from the lower end toward the center. The number of coils to whichthis variation in pitch is applied will depend on the characteristics orthe demands upon the particular engine with which the spring is used.For ordinary purposes, three coils are ample.

When partially compressed within the required lengths as shown inFigures 3 and 4 the lower coils 11 are shut or solid, while the upper oractive coils are left spaced from each other. As a result when thespring is in the valve open position as in Figure 4, the lower coils 11are closed or shut solid leaving the upper coils 12 to take care of theload deiiection necessary to operate the valves. As is shown at 13 inFigure 3, the uppermost coil of the lower coils 11 may be slightlyspaced from its adjacent coil, although this is not absolutely necessaryas all the coils 11 may be closed.

IvVith the spring deflections as shown in Figures 3 and 4 only the upperspaced coils 12 will tend to produce dancing or produce a surge, but bythe application of our new spring with the progressively varying pitch,any dancing7 or surge which may occur will be beyond the driving rangeof the motor.

The loads required at valve open and valve closed position, the heightto be occupied by the spring, and the allowable fiber stress, willdetermine the size of the wire, the diameter of the coil, total numberof coils, and the number of coils to be closed.

In designing a spring for an engine it is necessary to have a certainload at valve closed position, as shown in Figure 3, a largerpredetermined load at valve open position, Figure 4, and maintain afiber stress which is not so excessive.

While we prefer to have a progressively increasing pitch variation fromthe end toward the center of the spring, this pitch variation may bereversed and increase from an intermediate point on the spring towardthe end.

The lower coils need not necessarily be wound with a variable pitch butmay have a combination of constant and variable pitches and this isequally true of the upper coils, It is also within the scope of theinvention to place the progressively variable coils at the top of thespring and the constant coils at the bottom or in reverse of theposition shown in the drawings.

We claim:

1. In combination with a reciprocable valve, a coil springfor movingsaid valve in one direction, said spring having some of its coils ofprogressively increasing pitch, said progressively increasing pitchcoils being closed when the spring is in operative position.

2. In combination with a reoiproeable valve, a. coil spring for movingsaid valve in one direction, said spring having some of its coils ofprogressively increasing pitch, and the remaining coils of a constantpitch, said progressively inoreasin pitch coils being closed When thespring 1s in operative position.

In testimony whereof We ax our signatures.

BENTON CATALINE. EUGENE C. RICHARD.

